PREFACE.

The subjects of clays, kaolins, and the ceramic arts branch out in so many directions that the question often arises as to how much can properly be included in or excluded from their bibliography. Industries based upon clays range all the way from the manufacture of the commonest bricks, through drain-tiles, paving bricks, firebricks, furnace linings, retorts, crucibles, sewer pipes, sanitary ware, and all kinds of earthenware, terra-cotta, and chinaware, up to the finest of porcelains and enamels. One can therefore look at these matters from the point of view of the farmer, the architect, the civil or the sanitary engineer, the metallurgist, the artist, the chemist, the geologist, the anthropologist, or the archæologist. The question as to where to stop is thus constantly presenting itself. Under such circumstances it is impossible to meet very precisely one's own or anybody else's expectations. In preparing the present bibliography it has been my endeavor to give titles relating to all these phases of the subject except the prehistoric; and while there are many of that class also, a great deal relating to ancient Grecian, Etruscan, and archaic matter has been purposely omitted. Those in need of information on this branch of ceramics would do well to consult the bibliography published by the South Kensington Museum in 1885 (pp. 73-94), the Archäologische Zeitung, Archæologia, the (British) Archæological Journal, and other archæological publications.

It will occur to anyone acquainted with the technologic work done on clays of late years that many of the most important papers on this phase of ceramics, such as Senger's, are not mentioned here. The reason is that Senger's papers and many others of a similar kind are published only in the periodicals on clays, and if one attempted to list all the articles on clays published in those journals he would have to give a complete index of each of them throughout, and that, of course, is quite out of the question.

A large number of brief abstracts of articles from the clay journals are published in the Berg- und Hüttenmännische Zeitung. These I have not attempted to give. Résumés of importance are also given under the head of "Fortschritte in der Thonindustrie," and of "Neuerungen in der Thonwaarenindustrie," in Dingler's Polytechnisches Journal, and in Wagner's Jahres-Bericht der chemischen Technologie.